Currently, the double cold reduction technology is typically adopted for manufacturing thin and ultralow-carbon strip products for shadow mask, which are commonly applied to the field of picture tube. Chinese patent application of publication No. CN1717502A relates to a process for producing shadow mask material, a shadow mask from the shadow mask material and a picture tube including the shadow mask. The contents of elements in a billet related in the process are designed as C: ≦0.004 wt. %, Si: ≦0.03 wt. %, Mn: 0.1-0.5 wt. %, P: ≦0.02 wt. %, S: ≦0.02 wt. %, Al: 0.01˜0.07 wt. %, N: ≦0.0040 wt. %, B: ≦0.01 wt. %, Nb: ≦0.1 wt. % and Ti: 0.0001˜0.1 wt. % with the remainders composed of Fe and unavoidable impurities. In the patent, the billet is subjected to hot rolling, pickling and cold rolling, further to continuous annealing or box annealing so as to regulate the content of residual C to 0.003 wt. % or less, and still further to double cold reduction at a rolling ratio of 20 to 92%, such that a material for shadow mask is obtained.
A Chinese patent for invention with granted publication No. CN1141412C provides a process, which adopts ultralow-carbon steel (pure iron) or adds to ultralow-carbon steel with a few strong carbide formation elements, Ti or Ti and Nb, such that the carbon therein is present in the form of carbide, with sharp reduction of the solid solution carbon in the steel and improvement of the aging resistance, which guarantees the performance of its stamping formation, especially, the formation uniformity. Through reasonable design for the chemical compositions and adjustment for the optimal processing parameters, the performance and magnetism of the strip material for shadow mask is capable to meet the operating requirements. Nevertheless, due to the addition of expensive alloy elements, the production cost of steelmaking increases substantially, and also because of the added alloy elements, in order to anneal completely, the annealing temperature has to be very high, thereupon the production energy consumption is large. Besides, the patent cannot produce shadow mask strip with a thickness of less than or equal to 0.15 millimeters.